refactor(discord): replace Discord.Net bot login with a Discord webhook

CHANGELOG.md

@@ -87,10 +87,15 @@ Please ADD ALL Changes to the UNRELEASED SECTION and not a specific release
 - CloudFormation template restructured into the shared format, with parameters only where the deploy workflow passes them and all other settings in a Settings mapping (#427)
 - ECS application logs in /ecs/<ApplicationName>/ are kept for 30 days instead of never expiring, using the same LogRetentionInDays setting as the API Gateway access logs (#421)
 - The ECS service is now named after the application, so it can be found by name in the DiscordBots cluster (#421)
+- Discord notifications are sent through a channel webhook (Discord:WebhookUrl / DISCORD__WEBHOOKURL) instead of a Discord.Net bot login (#423)
+- Startup fails if the Discord webhook URL is missing or not an absolute https URL (#423)
+- Discord notifications are truncated to Discord's embed length limits instead of being rejected by Discord when a title, description, field or total length is exceeded (#423)
+- Push notifications show only the first line of each commit message instead of the full message (#423)
 ### Deprecated
 ### Removed
 - Removed NuGet audit suppressions for Scriban 6.2.0 vulnerabilities now that the transitive dependency has been dropped
 - TaskExecutionRole CloudFormation parameter (#419)
+- Discord.Net dependency, release channel support and the Discord:Token, Discord:Server, Discord:Channel and Discord:ReleaseChannel settings (#423)
 ### Deployment Changes
 - ECS service deployment circuit breaker with rollback, so tasks that fail to start (e.g. a missing secret key) fail the deploy quickly (#419)
 - ECS tasks now read their secrets at start-up using the ecsTaskExecutionRole execution role, which must have secretsmanager:GetSecretValue on the BuildBot secret (#419)
@@ -99,6 +104,7 @@ Please ADD ALL Changes to the UNRELEASED SECTION and not a specific release
 - This deploy replaces the ECS service, target group and listener rule (#421)
 - Payloads over 10 MB are rejected by API Gateway (#421)
 - The deploy user needs logs:PutRetentionPolicy on the /ecs/* log group, because the stack now sets a 30-day retention on it (#421)
+- The BuildBot Secrets Manager secret must contain a DISCORD_WEBHOOK key (an https Discord webhook URL) before deploying; the DISCORD_TOKEN, DISCORD_SERVER, DISCORD_CHANNEL and DISCORD_RELEASE_CHANNEL keys are no longer used (#423)
 
 <!--
 Releases that have at least been deployed to staging, BUT NOT necessarily released to live.  Changes should be moved from [Unreleased] into here as they are merged into the appropriate release branch

COVERAGE.md

@@ -8,13 +8,13 @@ Generated by the AI Coverage phase. Do not edit by hand.
 | --- | --- |
 | BuildBot | n/a (no instrumented lines) |
 | BuildBot.CloudFormation | 100.0% |
-| BuildBot.Discord | 96.8% |
+| BuildBot.Discord | 100.0% |
 | BuildBot.GitHub | 100.0% |
 | BuildBot.Health | 100.0% |
 | BuildBot.Json | 100.0% |
 | BuildBot.ServiceModel | 100.0% |
 | BuildBot.Watchtower | 100.0% |
-| **Overall (.NET)** | **99.2%** |
+| **Overall (.NET)** | **100.0%** |
 
 ## Node
 
@@ -30,4 +30,4 @@ excluded
 
 ---
 
-Captured at commit `5838d6adf7b290fa6688493d7b506ecb2b56ab84` on 2026-10-16.
+Captured at commit `21531fa8f8a0eaaa7c7981d2b08325401cbd5f8a` on 2026-10-19.

Dockerfile

@@ -1,4 +1,4 @@
-# chiseled-extra is needed over chiseled for Discord
+# chiseled-extra is needed over chiseled for ICU, as globalization invariant mode is disabled
 #FROM mcr.microsoft.com/dotnet/runtime-deps:9.0-noble-chiseled-extra
 FROM mcr.microsoft.com/dotnet/runtime-deps:11.0-resolute-chiseled-extra
 

README.md

@@ -13,6 +13,7 @@ FunFair's Build Discord Bot
 | Setting                | Environment variable    | Type   | Default | Description                                                                                                                                                                                                                                                                                                                                                  |
 |------------------------|-------------------------|--------|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `GitHub:WebhookSecret` | `GITHUB__WEBHOOKSECRET` | string | (empty) | Shared secret configured on the GitHub webhook, used to verify the HMAC-SHA256 `X-Hub-Signature-256` header on `/github/*` requests. Requests with a missing or invalid signature are rejected with 401. When empty, signatures are not verified and a warning is logged at startup. In AWS it is read from the Secrets Manager key `GITHUB_WEBHOOK_SECRET`. |
+| `Discord:WebhookUrl`   | `DISCORD__WEBHOOKURL`   | URL    | (empty) | Discord channel webhook URL that build, deployment and container messages are posted to. Required: startup fails if it is empty or not an absolute `https` URL. The URL contains the webhook token, so treat it as a secret. In AWS it is read from the Secrets Manager key `DISCORD_WEBHOOK`.                                                               |
 
 ## Deployment
 

cloudformation.json

@@ -94,61 +94,10 @@
             ],
             "Secrets": [
               {
-                "Name": "DISCORD__TOKEN",
+                "Name": "DISCORD__WEBHOOKURL",
                 "ValueFrom": {
                   "Fn::Sub": [
-                    "${SecretsManagerArn}:DISCORD_TOKEN::",
-                    {
-                      "SecretsManagerArn": {
-                        "Fn::FindInMap": [
-                          "Settings",
-                          "Values",
-                          "SecretsManagerArn"
-                        ]
-                      }
-                    }
-                  ]
-                }
-              },
-              {
-                "Name": "DISCORD__SERVER",
-                "ValueFrom": {
-                  "Fn::Sub": [
-                    "${SecretsManagerArn}:DISCORD_SERVER::",
-                    {
-                      "SecretsManagerArn": {
-                        "Fn::FindInMap": [
-                          "Settings",
-                          "Values",
-                          "SecretsManagerArn"
-                        ]
-                      }
-                    }
-                  ]
-                }
-              },
-              {
-                "Name": "DISCORD__CHANNEL",
-                "ValueFrom": {
-                  "Fn::Sub": [
-                    "${SecretsManagerArn}:DISCORD_CHANNEL::",
-                    {
-                      "SecretsManagerArn": {
-                        "Fn::FindInMap": [
-                          "Settings",
-                          "Values",
-                          "SecretsManagerArn"
-                        ]
-                      }
-                    }
-                  ]
-                }
-              },
-              {
-                "Name": "DISCORD__RELEASE_CHANNEL",
-                "ValueFrom": {
-                  "Fn::Sub": [
-                    "${SecretsManagerArn}:DISCORD_RELEASE_CHANNEL::",
+                    "${SecretsManagerArn}:DISCORD_WEBHOOK::",
                     {
                       "SecretsManagerArn": {
                         "Fn::FindInMap": [

src/BuildBot.CloudFormation.Tests/Publishers/CloudFormationMessageReceivedNotificationHandlerTests.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using BuildBot.CloudFormation;
@@ -215,4 +216,97 @@ CloudFormationMessageReceivedNotificationHandler handler
 
         await mediator.Received(1).Publish(Arg.Any<BotMessage>(), Arg.Any<CancellationToken>());
     }
+
+    private static DiscordEmbed PublishedEmbed(IMediator mediator)
+    {
+        return mediator
+            .ReceivedCalls()
+            .Select(static call => call.GetArguments()[0])
+            .OfType<BotMessage>()
+            .Single()
+            .Message;
+    }
+
+    private async Task<DiscordEmbed> PublishAsync(Deployment deployment, StackDetails? stackDetails)
+    {
+        (
+            _,
+            ICloudFormationDeploymentExtractor extractor,
+            IAwsCloudFormation aws,
+            IMediator mediator,
+            CloudFormationMessageReceivedNotificationHandler handler
+        ) = this.CreateHandler();
+
+        extractor.ExtractDeploymentProperties(Arg.Any<CloudFormationMessageReceived>()).Returns(deployment);
+        aws.GetStackDetailsAsync(Arg.Any<Deployment>(), Arg.Any<CancellationToken>()).Returns(stackDetails);
+
+        await handler.Handle(notification: MakeNotification(VALID_ARN), cancellationToken: this.CancellationToken());
+
+        return PublishedEmbed(mediator);
+    }
+
+    [Fact]
+    public async Task Handle_WithoutStackDetails_PublishesExpectedEmbed()
+    {
+        DiscordEmbed embed = await this.PublishAsync(deployment: MakeDeployment(), stackDetails: null);
+
+        Assert.Equal(expected: "MyProject was deployed ", actual: embed.Title);
+        Assert.Equal(
+            expected: new Uri(
+                "https://eu-west-1.console.aws.amazon.com/cloudformation/home?region=eu-west-1#/stacks/stackinfo?stackId=arn:aws:cf:eu-west-1:123:stack/MyStack/x"
+            ),
+            actual: embed.Url
+        );
+        Assert.Null(embed.Description);
+        Assert.Equal(expected: 0x2ECC71u, actual: embed.Color?.Value);
+        Assert.Equal(
+            expected:
+            [
+                new DiscordEmbedField(Name: "ARN", Value: "arn:aws:cf:eu-west-1:123:stack/MyStack/x"),
+                new DiscordEmbedField(Name: "Status", Value: "UPDATE_COMPLETE"),
+            ],
+            actual: embed.Fields
+        );
+    }
+
+    [Fact]
+    public async Task Handle_WithFailedDeploymentAndStackDetails_PublishesExpectedEmbed()
+    {
+        Deployment deployment = MakeDeployment() with { Status = "UPDATE_FAILED", Success = false };
+
+        DiscordEmbed embed = await this.PublishAsync(
+            deployment: deployment,
+            stackDetails: new StackDetails(Description: "A deployment", Version: "2.0.0")
+        );
+
+        Assert.Equal(expected: "MyProject (2.0.0) failed to deploy", actual: embed.Title);
+        Assert.Equal(expected: "A deployment", actual: embed.Description);
+        Assert.Equal(expected: 0xE74C3Cu, actual: embed.Color?.Value);
+        Assert.Equal(
+            expected:
+            [
+                new DiscordEmbedField(Name: "ARN", Value: "arn:aws:cf:eu-west-1:123:stack/MyStack/x"),
+                new DiscordEmbedField(Name: "Status", Value: "UPDATE_FAILED"),
+                new DiscordEmbedField(Name: "Version", Value: "2.0.0"),
+            ],
+            actual: embed.Fields
+        );
+    }
+
+    [Fact]
+    public async Task Handle_WithStackDetailsButNoVersion_OmitsVersionField()
+    {
+        DiscordEmbed embed = await this.PublishAsync(
+            deployment: MakeDeployment(),
+            stackDetails: new StackDetails(Description: "A deployment", Version: null)
+        );
+
+        Assert.Equal(expected: "MyProject was deployed ", actual: embed.Title);
+        Assert.Equal(expected: "A deployment", actual: embed.Description);
+        Assert.Equal(
+            expected: ["ARN", "Status"],
+            actual: embed.Fields.Select(static f => f.Name),
+            comparer: StringComparer.Ordinal
+        );
+    }
 }

src/BuildBot.CloudFormation/Publishers/CloudFormationMessageReceivedNotificationHandler.cs

@@ -7,7 +7,6 @@
 using BuildBot.CloudFormation.Models;
 using BuildBot.CloudFormation.Publishers.LoggingExtensions;
 using BuildBot.Discord.Models;
-using Discord;
 using Mediator;
 using Microsoft.Extensions.Logging;
 
@@ -67,29 +66,22 @@ public async ValueTask Handle(CloudFormationMessageReceived notification, Cancel
         );
 
         this._logger.BuildingMessage(deployment.Value);
-        EmbedBuilder embed = BuildStatusMessage(deployment: deployment.Value, stackDetails: stackDetails);
+        DiscordEmbed embed = BuildStatusMessage(deployment: deployment.Value, stackDetails: stackDetails);
 
         this._logger.PublishingMessage(deployment.Value);
 
         await this._mediator.Publish(new BotMessage(embed), cancellationToken: cancellationToken);
     }
 
-    private static EmbedBuilder BuildStatusMessage(in Deployment deployment, StackDetails? stackDetails)
+    private static DiscordEmbed BuildStatusMessage(in Deployment deployment, StackDetails? stackDetails)
     {
-        EmbedBuilder builder = new EmbedBuilder()
-            .WithTitle(BuildTitle(deployment: deployment, stackDetails: stackDetails))
-            .WithUrl(BuildStackUrl(deployment).ToString())
-            .WithColor(deployment.Success ? Color.Green : Color.Red)
-            .WithFields(GetFields(deployment));
-
-        if (stackDetails is not null)
-        {
-            builder
-                .WithDescription(stackDetails.Value.Description)
-                .AddField(name: "Version", value: stackDetails.Value.Version);
-        }
-
-        return builder;
+        return new(
+            Title: BuildTitle(deployment: deployment, stackDetails: stackDetails),
+            Url: BuildStackUrl(deployment),
+            Description: stackDetails?.Description,
+            Color: deployment.Success ? DiscordColor.Green : DiscordColor.Red,
+            Fields: GetFields(deployment: deployment, stackDetails: stackDetails)
+        );
     }
 
     private static string BuildTitle(in Deployment deployment, StackDetails? stackDetails)
@@ -113,18 +105,26 @@ private static Uri BuildStackUrl(in Deployment deployment)
         );
     }
 
-    private static IReadOnlyList<EmbedFieldBuilder> GetFields(in Deployment deployment)
+    private static IReadOnlyList<DiscordEmbedField> GetFields(in Deployment deployment, StackDetails? stackDetails)
+    {
+        DiscordEmbedField[] fields = [AddArnEmbed(deployment), AddStatusEmbed(deployment)];
+        string? version = stackDetails?.Version;
+
+        return string.IsNullOrWhiteSpace(version) ? fields : [.. fields, AddVersionEmbed(version)];
+    }
+
+    private static DiscordEmbedField AddArnEmbed(in Deployment deployment)
     {
-        return [AddArnEmbed(deployment), AddStatusEmbed(deployment)];
+        return new(Name: "ARN", Value: deployment.Arn);
     }
 
-    private static EmbedFieldBuilder AddArnEmbed(in Deployment deployment)
+    private static DiscordEmbedField AddStatusEmbed(in Deployment deployment)
     {
-        return new EmbedFieldBuilder().WithName("ARN").WithValue(deployment.Arn);
+        return new(Name: "Status", Value: deployment.Status);
     }
 
-    private static EmbedFieldBuilder AddStatusEmbed(in Deployment deployment)
+    private static DiscordEmbedField AddVersionEmbed(string version)
     {
-        return new EmbedFieldBuilder().WithName("Status").WithValue(deployment.Status);
+        return new(Name: "Version", Value: version);
     }
 }

src/BuildBot.Discord.Tests/DependencyInjectionTests.cs

@@ -1,8 +1,7 @@
-using BuildBot.Discord;
+using System;
 using BuildBot.Discord.Models;
 using BuildBot.Discord.Services;
 using BuildBot.ServiceModel.ComponentStatus;
-using Discord;
 using FunFair.Test.Common;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
@@ -12,11 +11,8 @@ namespace BuildBot.Discord.Tests;
 
 public sealed class DependencyInjectionTests : DependencyInjectionTestsBase
 {
-    private static readonly DiscordBotConfiguration TestConfig = new(
-        token: "test-token",
-        server: "test-server",
-        channel: "test-channel",
-        releaseChannel: "test-release-channel"
+    private static readonly DiscordBotConfiguration TestConfig = DiscordBotConfiguration.FromWebhookUrl(
+        "https://example.com/webhook"
     );
 
     public DependencyInjectionTests(ITestOutputHelper output)
@@ -40,44 +36,32 @@ public void DiscordBotMustBeRegisteredAsIComponentStatus()
     }
 
     [Fact]
-    public void BotMessageChannelMustBeRegistered()
-    {
-        this.RequireService<IMessageChannel<BotMessage>>();
-    }
-
-    [Fact]
-    public void BotReleaseMessageChannelMustBeRegistered()
+    public void DiscordWebhookClientMustBeRegistered()
     {
-        this.RequireService<IMessageChannel<BotReleaseMessage>>();
+        this.RequireService<IDiscordWebhookClient>();
     }
 
     [Fact]
-    public void BotServiceMustBeRegisteredAsIHostedService()
+    public void TimeProviderMustBeRegistered()
     {
-        this.RequireService<IHostedService>();
+        this.RequireService<TimeProvider>();
     }
 
     [Fact]
-    public void DiscordRawClientMustBeRegistered()
+    public void ConfigurationMustBeRegistered()
     {
-        this.RequireService<IDiscordRawClient>();
+        this.RequireService<DiscordBotConfiguration>();
     }
 
     [Fact]
-    public void DiscordRawClient_WhenDisconnected_LoginStateIsLoggedOut()
+    public void BotMessageChannelMustBeRegistered()
     {
-        IDiscordRawClient client = this.GetService<IDiscordRawClient>();
-        Assert.Equal(expected: LoginState.LoggedOut, actual: client.LoginState);
+        this.RequireService<IMessageChannel<BotMessage>>();
     }
 
     [Fact]
-    public void FindChannel_WhenClientIsDisconnected_ReturnsNull()
+    public void DiscordMessageSenderMustBeRegisteredAsIHostedService()
     {
-        IDiscordRawClient client = this.GetService<IDiscordRawClient>();
-        IDiscordChannel? channel = client.FindChannel(
-            serverName: "nonexistent-server",
-            channelName: "nonexistent-channel"
-        );
-        Assert.Null(channel);
+        this.RequireService<IHostedService>();
     }
 }